Drafters of overhaul plans had been considering the issue for months, and it gained new attention during Obama's healthcare speech to Congress. But enforcement is fraught with its own problems.

WASHINGTON AND LOS ANGELES — Key members of the Senate Finance Committee moved Friday to quell the latest furor over President Obama's healthcare overhaul, discussing added identification and enforcement requirements intended to prevent illegal immigrants from receiving federal benefits.

Committee members ended their closed-door deliberations without reaching agreement on a response, but they are scheduled to work into the weekend.

The concern is whether the proposals being worked out by congressional Democrats with Obama's support would make benefits available directly or indirectly to people who are in the United States illegally.

The controversy centers primarily on plans to provide government funds to help low-income workers get affordable insurance coverage.

Though drafters of the evolving healthcare bills have been considering the issue for months, it was catapulted into the national spotlight Wednesday night during Obama's address to a joint session of Congress.

When the president said that his blueprint would not aid illegal immigrants, Rep. Joe Wilson (R-S.C.) shouted, "You lie!" Wilson has since apologized for his breach of congressional courtesy, but the episode touched off a vociferous debate over the issue.

Democrats note that both the House and Senate versions of the bill already contain language that specifically bars illegal immigrants from receiving federal help to purchase healthcare coverage.

Republicans counter that a written ban means little without tough enforcement provisions, which they say Democrats have refused to include. At their meeting Friday, members of the Senate Finance Committee discussed adding enforcement safeguards to their bill, which will be presented as soon as Tuesday.

It is unclear what such provisions should be, and whether they would guarantee that no illegal immigrants receive subsidized insurance.

Under the Democrats' plans, the government would subsidize the expansion of insurance coverage in two ways.

First, the Medicaid program, which covers healthcare for the poor, would be expanded to include those whose income is just above the poverty level. Since 2006, new participants in Medicaid have been required to prove that they are U.S. citizens or eligible legal residents by supplying a passport, a U.S. birth certificate or other official documents.

The verification rules would apply to the expanded Medicaid program under the Democrats' proposals.

(There is one major exception to rules preventing benefits for illegal immigrants. The government requires hospitals to provide care for emergency patients in severe pain, and in certain circumstances Medicaid will pay for poor patients' emergency care regardless of their immigration status.)

Second, the government, beginning in 2013, would subsidize insurance, including private policies, for low- and middle-income Americans who do not qualify for Medicaid. These subsidies are referred to as "affordability credits" in the House bill.

"Nothing in this subtitle shall allow federal payments for affordability credits on behalf of individuals who are not lawfully present in the United States," the bill says.

In July, Democrats rejected a Republican-sponsored amendment that would have required buyers of this subsidized insurance to supply official documents to prove they are legal residents.

The Democrats said that requiring this sort of proof would put a costly burden on private insurance companies, and that they feared it would deter low-income Americans from buying health insurance. They voted instead to have a future federal health official devise rules to prevent illegal immigrants from obtaining the insurance subsidies.

"The bill says the benefits should not go to illegal aliens, but the Democrats voted down every amendment to enforce that," said Rep. Joe L. Barton (R-Texas).

Sonal Ambegaokar, a lawyer for the National Immigration Law Center, said that verification provisions would add layers of unnecessary government red tape to a system that is already overly bureaucratic, and would keep low-income people who qualify for insurance, and who often don't have necessary documents at hand, from obtaining it.

"Don't we want to simplify the system?" Ambegaokar said. "We already have a lot of paperwork in the system, and I thought the goal of reform was to reduce administrative costs."

Ambegaokar said that anti-immigration forces were seeking to hijack the debate over healthcare reform. "Healthcare and immigration are really two broken systems, and people are frustrated," she said.

Frank Sharry of America's Voice, a Washington-based immigrant rights organization, said that studies had shown that additional verification systems cost more than they save.

One congressional oversight committee found that a 2005 federal law requiring more extensive documentation of legal immigration status for Medicare recipients cost $16.6 million in new administrative expenses for six of nine states surveyed in 2009.

A 2007 study by the Government Accountability Office found that half of the 44 states surveyed said the new requirements had resulted in a decline in Medicare recipients, but most of those affected were believed to be citizens or eligible legal residents.